Behavior Brief

The water boatman (Micronecta scholtzi), above, is only 2mm long but is the loudest animal ever to be recorded, relative to its body size.JEROME SUEUR

Pealing penis

The tiny water boatman, Micronecta scholtzi, is the world’s loudest animal relative to its size and the surprisingly noisy song originates from the animal’s penis, according to research published last month (June 15) in PLoS One. The bug runs its “genitalia appendage,” as the authors call it, along groves in its abdomen to produce the cricket-like song (listen). The mating call peaks at 99.2 decibels, which is the equivalent of sitting in the front row of a loud orchestra or standing 15 meters from a hurtling freight train, Wired reports. (Hat tip to ScienceNOW.)

Lizards as smart as birds

Little green anoles solve complex tasks just as well as birds and mammals, researchers reported yesterday (July 12) in Biology Letters, challenging the belief that reptiles have limited cognitive abilities. Duke University researcher Manuel Leal tested Puerto Rican anoles with a problem-solving task usually used on birds—and they performed even better: On a wooden block with two wells covered by different colored caps, one empty and one containing a worm, four lizards learned to flip the correct cap in three fewer attempts than birds typically take to do so. Their success was "completely unexpected," Leal said in a press release. Anoles are considered “large-brained” lizards and have been known to exhibit other complex behaviors, but lizards are typically thought to have limited cognitive abilities.

Extra-marital affairs are a viable reproductive strategy not only for gerbils, birds, marmosets and other socially monogamous animals, but also for humans, new research suggests. In a study of the Himba, a group of traditional Namibian herders in Africa, Brooke Scelza at the University of California, Los Angeles, found that 17 percent of all births are due to extramarital affairs—the highest rate yet reported in humans—and having children outside of wedlock was associated with significant increases in women's reproductive success. Context was important, Scelza found: the 30 percent of women who report having at least one child through an affair were all in arranged marriages, rather than love matches. The study was published last week (July 6) in Biology Letters.

Eastern chipmunks (Tamias striatus)

HOLLY OWEN

Cross-specieseavesdropping

Humans aren’t the only ones who like to listen in on their neighbors. Eastern chipmunks take heed of woodchucks’ alarm calls and vice versa, according to a June study in the Journal of Mammology. Woodchuck alarms sent chipmunks fleeing to their burrows, Wired reports, and woodchucks responded to chipmunk alarm calls as well, though with less activity.

A group of ground-nesting birds called overbirds also monitor chipmunk communication, but not for increased vigilance against predators. These birds eavesdrop to help determine the safest place to nest—as far away as possible from the egg-guzzling rodents. In a recent study from the Journal of Animal Ecology, scientists played recordings of chipmunk calls at 28 locations in the Hudson Valley in New York. Ovenbirds nested much further away from plots where the calls were played compared with controls.

Interrupting monkeys

WIKIMEDIA COMMONS, BADGERNET

Monkeys learn not to interrupt their elders, just like human children, according to a June 23 study in Scientific Reports, adding another parallel between human conversations and non-human primates' vocal exchanges. The scientists found that adult Campbell's monkeys (Cercopithecus campbelli) broke the rules of alternating calls only one percent of the time, while juveniles broke the rules in 13 percent of their calls, reports ScienceNOW.

Old spiders weave erratic webs

Left: Web woven by a 17-day-old spider. Right: Web woven by a 188 day old spider

MYLENE ANOTAUX

Spiders weave messier webs as they age, researchers reported at the Society for Experimental Biology annual conference in Glasgow in early July. The finding is one example of how age affects behavior, and could potentially translate to humans. Young European house spiders, Zygiella x-notata, weave precise webs with regular patterns and sharp angles, while their older counterparts construct irregular webs full of holes. "Our next steps will be to understand whether age-induced changes in the central nervous system are behind the differences in behavior we have found," said author Mylène Anotaux, from Nancy University in France in a press release. If so, the research could help scientists identify if similar mechanisms affect human behavior in later life.